Dowel pin relator



July 15, 1958 E. E. CARLSON 2,842,845

DOWEL PIN RELATOR Filed Oct. 6. 1954 INVENTOR final [Java/"d Car/son A TTORNEY nite State spasms DQWEL FHN transi ion This invention relates to prosthodontics. More particularly, the invention concerns an improvement in a pinledge guide and retainer or dowel pin paralleling instrument and impression tray combination for making inlays, crowns or bridges and reconstruction work, and a method of using improved hydrocolloid technique by dental technicians.

The centering and paralleling of dowel pins in the impressions of the prepared teeth is one of the necessary mechanical steps in the construction of dies and must be accomplished with extreme accuracy. To perform this operation a number of diiferent type mandrels and clamps have been devised to align dowel pins in the die models on impression trays. Such mandrels and clamps are of the character as disclosed in the publications Crown and Bridge Construction Using Hydrocolloid Impressions by J. F. Jelenko & Co., Inc., and Practical Application of Hydrocolloid for Fixed Bridgework, a reprint by The J. M. Ney Company. The trays with which these instruments are used are provided with a water jacket and are separable from the pin aligner for placement in a sulfate bath or humidor for conditioning by the usual process as illustrated in the above Works.

In contrast to the usual practice it is found that it is better to constantly maintain the tray and dowel pin alignment throughout the process of preparing inlays and artificial teeth.

Accordingly, it is an object of this invention to provide an improved dowel pin relator.

Another object is to provide an improved combination of impression trays and a dowel pin relator.

An additional object of this invention is to provide an improved method of maintaining dowel pin alignment with an impression tray during the process of making the tooth die.

Another object is to provide an improved method of centering and paralleling dowel pins in prepared teeth.

A further object is to provide an improved arrangement of tray and dowel alignment structure preventing displacement and subsequent distortion, misalignment and irregular strains in hydrocolloid for stone dies.

Further objects and advantages will be apparent from the following description relating to the accompanying drawings, wherein:

Figure 1 is a side perspective of the impressiontray in combination with the dowel pin relator as embodied in any disclosure.

Figure 2 is a modification of Figure 1.

Figure 3 is a further partial modification illustrating a dowel pin holder.

Figure 4 is a perspective of a relator mounting clamp.

Figure 5 is a partial frontal. perspective of the relator holding clamp shown in Figure 1.

Figure 6 is a partial perspective of a clamp screw and holder for the relator arm.

In the following description like parts will be similarly indicated.

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As known to the technician and indicated in the above publications, the very technical precision of making inlays and artificial teeth is dependent upon many factors including formation of the mold and die while maintaining accurate centering and paralleling of the dowel pin. It is, of course, apparent that where the dowel pins are repeatedly repositioned or moved from off center that strains occur causing maladjustment and defections in the formed product.

In forming the molded product it is preferable to use an impression tray 10 of the solid water-jacket type with or without perforations. The tray 10 shown in Figure l is a complete plate type and the tray 11 is a partial plate type. In either case the trays 10 and 11 are provided with water inlet and water outlet conduits 12, 13 and illustrative arms 14, respectively, which serve as supporting structure for mounting the dowel pin relator. Otherwise the conduits serve as holding arms for the dowel pin relator as herein described and accordingly may be termed as a tray attachment which facilitates the combination of the tray and relator.

Inasmuch as the making of the die impression is the usual procedure preliminary to setting of the dowel pins in the hydrocals or die stones, this improvement in the art will be described from the point of time when such hydrocal is poured into the hydrocolloid impressions on the tray. Presuming the impressions to be formed, a mechanical vibrator is usually used to vibrate the hydrocal or die stones into a confining matrix on the impression tray 19 or 11. The hydrocal and model or die stone materials are commercial preparations well known to the impression technicians and available for use in the making of teeth and inlay dies.

Taking, for example, that the tray 10 is provided with a formed matrix, a U-shaped clamp 15, with top 16 and bottom 17 as opposite sides and side 17 being provided with one or more guide grooves 18, is securely mounted on the arms 12 and 13. The screw threaded bolt 19 is provided at one end with head 20 and at the opposite end with an opening or socket 21 of the allen type which firmly holds and secures arm 22 therein. A flexible compression spring 23 having one end 24 wrapped about the threaded bolt 19 and its opposite U-shaped end 25, pressing against arm 22, locks and holds the end 26 of arm 22 in opening 21. Finger pressure, directly or indirectly against the compressive force of spring 23 will release the end 26 from opening 21.

As illustrated in Figure l, the screw threads of bolt 19 are turned through a pair of central aligned openings 27 (one opening only being'shown in the top plate section 16) in the plate 15 with threads of bolt 19 bearing against and turning about the relatively flexible ends of a pair of similar tongues 28. The bolt 19 may be screwed through the opening 27 by the allen type fitting of arm 22 or turning of head 20.

There is clamped or otherwise secured, by welding or the like, to the outer free end of arm 22, a plate 28 provided with a plurality of rows or aligned series of apertures or perforations 29, serving as mandrel or dowel pin guides, which are relatively adjustable to and held in a steadfast position over the impression tray 10. The perforations 29 are slightly larger than the mandrel 39 which extends therethroug'h to align and hold the dowel pin 31 centered or at an angle exactly in a position desired in the impression, for example 32' After an exact placement of the dowel pin 31 is obtained, a plastic material as a wax or parafiin filling 32 is forced into the perforation 29 and about the mandrel 30 to firmly secure mandrel 30- and hold the pin 31 in place. In this illustration it will be understood that only one mandrel, dowel pin and impression is demonstrated and that where a group of inlays or teeth are to be formed the perforations 29 are aligned over the tray and any proper number of dowel pins can then 'be centered and paralleled, or angularly aligned, in the ging or root stump of the teeth impressions. Further the screw threads 19 allow for some variation of adjustment or placement of the apertures 29 over the impressions in the mold tray 1% The manner of inserting the dowel pin 31 into the root apex of the die stone is by aligning over the tray the relator pin in perforation 29 with the head of the dowel pin close to the ging of a prepared tooth impression cavity, securing the mandrel 30, and after alignment removing the relator arm 22 from the socket in the bolt 19. Die stone is then carefully vibrated into the cavity in the impression and building up a slight excess of stone is built up at the point at which the tip of the dowel pin is to be inserted. Thereafter the arm is replaced in the opening 21 and the positioned dowel pin 30 is reset into its exact original position relative to the tray 10. The end of the dowel pin 31 is coated or covered with wax in the usual manner and is then gently pressed into the stone in its exact pre-set position. The hydrocal or stone material is then shaped or built up about the dowel pin and the whole assembly of tray and relator is immersed into a potassium sulfate solution or placed in a humidifier for setting the material in the tray in the conventional manner. For example, the poured impression is placed in the potassium sulfate or humidor for a sufficient period of time to permit the stone to set. As indicated in the Jelenko publication, at minimum of forty minutes for setting is preferred. Thereafter, the relator maintaining its dowel pin alignment is placed in a humidor, or the formed material worked upon in the usual manner while maintaining the 'tray in its exact aligned relationship with respect to the pin guide and relator structure.

Otherwise the die stone may be vibrated into each cavity preparation, then, after setting, the dies are cut from the mold form and the root portion of the die is ground down to a taper. drilled into the apex of the root and a dowel pin is cemented in the hole. Thereafter, the die and dowel pin are coated lightly with petroleum jelly and reinserted into the impression. A mandrel 30 is positioned through perforation 29 onto the dowel pin and then set or held by molding wax 32 in a relatively permanent relationship with respect to the tray 10. Thereby the dowel pin or dowel pins are mounted in the prepared teeth or inlay forms and are maintained in an originally placed or replaceable position in the tray and with respect to each other.

As illustrated in Figure 2 the tray 11 is provided with the extended holding conduit arms 14 which serve as supports for the inserts 33 and 34. The inserts 33 and 34- provide a mount for the hollow standard 35 providing a socket into which a depending section 36 of arm 37 is inserted. The lower end of arm section 36 is provided with a pin 38 which slides into the slot 39. The pin 38 and slot 39 serve to hold plate 28 and the rows or series of perforations 29 in a replaceable alignment over the tray 11. This tray 11 is of the character used in making a partial plate and the dowel pin or pins with their holding mandrel or mandrels are aligned and held in a steadfast position with a molding wax in the manner as heretofore described.

A modified form of a mandrel holding plate 40 is shown in Figure 3. The perforations provided in plate 40 constitute a series of parallel slots 41 which permit one or more pin mandrels 30 tobe initially shifted or positioned to a proper dowel pin holding angle and then set in a relatively permanent relationship to the holding tray by a molding wax or plastic 32 as illustrated in Figure l. The arm 22 is preferably of the character as shown for arm 22 in Figure l and is likewise attached to either solid or hollow arm 12' and 13 of tray 10.

Thereafter, a small hole is I Otherwise the arm 22 may be similar to the arm 37, as

- shown in Figure 2, and attached in the manner as illustrated therein.

There is also illustrated in Figure 4 a modified relator U-shaped holding clamp 15 formed of a bent metal piece with correspondingly extended top section 16 and bottom section 17. Similiarly an opening 27' with extended tongues 28 is provided for receiving the screw bolt 19 and an extended side 18 of top 16 is bent down wardly and inwardly with a rounded guide surface for the tray arm 13. A similar guide opposite 18 (not shown) may be provided for the other arm 12, if desired.

As heretofore indicated, the process of obtaining and maintaining a proper alignment of the dowel pin in the tooth model has been a major problem in this field. Improper alignment of the tray, dowel pin and model has heretofore been a primary cause in the building of imperfect fitting inlays and artificial teeth. Thus great skill has heretofore been required to obtain proper dowel pin placement and alignment in the production of individual teeth dies from hydrocolloid impressions made in the holding tray. Now with the present arrangement of structure in the new combination, as described, a proper alignment of the dowel pins is obtained which does not require a skilled technician and saves time and labor without faulting or building imperfect models and teeth.

In accordance with the patent statutes, I have described the principles of construction and operation of my improvement in a pin ledge guide and retainer or dowel pin paralleling instrument and impression tray combination for making inlays and false teeth, and while I have endeavored to set forth the best embodiment thereof, I desire to have it understood that changes may be made within the scope of the following claims without departing from the spirit of my invention.

I claim:

1. A dowel pin relator in combination with a model tray for building artificial teeth impressions comprising a model tray, a holding arm on said tray, a clamp mounted on said holding arm, a standard mounted on said clamp, a frame mounted on said standard and supported in an exact replaceable position over said model tray, said frame including openings for aligning and setting dowel pins in tooth models in said tray, and holding means securing said dowel pins in a pre-set alignment in said openings.

2. A relator for centering and paralleling dowel pins in a relatively stationary and exact replaceable position over a tray for building artificial teeth and inlay impressions comprising a clamping bracket for attachment to the tray, a standard on said bracket, an arm supported by said standard and a perforated plate carried by said arm for holding dowel pins in alignment over teeth impressions in said tray.

3. A dowel pin relator for use with a dowel pin supporting means including in combination a dental impression tray having arm means secured thereto and projecting therefrom, a bracket means detachably secured in fixed relation to said arm means, an arm detachably secured in a pre-set fixed relation to said bracket, and a perforated plate connected to said arm and supported to overlie said tray, whereby said dowel pin supporting means may be inserted through a perforation in said plate and secured in proper relation to said impression tray, and whereby said arm and plate may be detached from said bracket and returned to said pre-set position.

4. The structure of claim 3 and in which the perforations in said plate are of larger dimensions than the dowel pin supporting means so that the dowel pin supporting means may be angularly adjustable relative to said plate.

5. The structure of claim 3 and in which the bracket means is detachabiy secured in predetermined position relative to said arm means.

-6. The structure of claim 3 and in which said arm means comprise tubular means through which liquid may flow, and in which said tray includes a water jacket into which said tubular means communicates.

7. The structure of claim 3 and in which said bracket: includes a socket member into which said arm extends,

References Cited in the file of this patent UNITED STATES PATENTS Sorensen Aug. 26, 1919 Mann Feb. 23, 1954 

